CN108169208A - A kind of Raman spectrum detector calibration method - Google Patents

Abstract

A method for calibrating a Raman spectrometer, comprising the following steps: Step 1, obtain a reference spectrum S1; Step 2, obtain an initial spectrum S2; Step 3, obtain a current background spectrum S3; Step 4, calculate the reference spectrum S1 and The first difference spectrum Sd1 of the initial spectrum S2, calculate the second difference spectrum Sd2 between the reference spectrum S1 and the current background spectrum S3, and calculate the third difference between the initial spectrum S2 and the current background spectrum S3 Spectrum Sd3; Step 5, determine the first offset Δv1 and the second offset Δv2; Step 6, use the first offset Δv1 to correct the Raman spectrum of the detection result or use the first offset Δv1 The four offsets △v4 correct the Raman spectrum of the detection result. The invention has the advantages of many calibration references, high calibration degree and good real-time performance.

Description

A kind of Raman spectrometer calibration method

technical field

The invention relates to the technical field of Raman spectrum detection, in particular to a method for calibrating a Raman spectrum detector.

Background technique

The wavelength of the laser of the Raman spectrometer is usually determined by calibration measurement when the laser leaves the factory or when the Raman spectrometer leaves the factory. However, the wavelength of the laser will drift slightly due to ambient temperature and fluctuations in electronic circuits. Lasers used in Raman spectrometers usually have high requirements on the stability of the laser wavelength, requiring ±2cm-1 or higher, and its stability parameters directly affect the Raman shift measurement accuracy of the instrument. After the Raman spectrometer leaves the factory, the laser wavelength may drift after long-term use, environmental changes, and long-distance transportation. Usually, the laser wavelength is corrected by self-calibration and other methods. The usual self-calibration method is: measure the Raman spectrum of a certain standard substance (such as polystyrene), and compare it with the standard spectrum of the standard substance, and then know the offset of the laser wavelength. The disadvantage of the existing self-calibration method is that it does not have real-time performance, only a constant correction value can be given, and it is difficult to grasp the conditions for self-calibration under what conditions.

Contents of the invention

The purpose of the present invention is to provide a method for calibrating a Raman spectroscopic detector, and the present invention provides a method that can quickly perform on-site calibration.

The above-mentioned technical purpose of the present invention is achieved through the following technical solutions: a method for calibrating a Raman spectrometer, comprising the following steps,

Step 1, use the Raman spectrometer to sample the signal of the standard reference substance in the T time period to obtain the reference spectrum S1;

Step 2, using a Raman spectrometer to sample the signal of the substance to be detected in the T time period to obtain an initial spectrum S2;

Step 3, using a Raman spectrometer to sample the signal of the T time period in the empty sample cell to obtain the current background spectrum S3;

Step 4, calculating the first difference spectrum Sd1 between the reference spectrum S1 and the initial spectrum S2, calculating the second difference spectrum Sd2 between the reference spectrum S1 and the current background spectrum S3, and calculating the difference between the initial spectrum S2 and the Describe the third difference spectrum Sd3 of the current background spectrum S3;

Step 5: Determine the reference laser spectrum peak and the laser spectrum peak of the object to be detected according to the second difference spectrum Sd2 and the third difference spectrum Sd3 respectively, and determine the reference laser spectrum peak and the object to be detected according to the The center positions of the laser spectrum peaks respectively determine the first offset Δv1 and the second offset Δv2;

Step 6, comparing the first offset Δv1 with the second offset Δv2, if they are equal, use the first offset Δv1 to correct the Raman spectrum of the detection result; if they are not equal Then determine the difference laser spectrum peak according to the first difference spectrum Sd1, then determine the third offset Δv3 according to the center position of the difference laser spectrum peak, and use the third offset Δv3 to determine The above offset Δv1 is corrected to obtain a fourth offset Δv4, and finally the Raman spectrum of the detection result is corrected by using the fourth offset Δv4.

As a preference of the present invention, the step five also includes directly correcting the detection result vf of the standard reference object by using the first offset Δv1, and comparing the correction result with the standard Raman spectrum to obtain The fifth offset Δv5, using the fifth offset Δv5 to correct the first offset Δv1 and the second offset Δv2 to obtain the final first offset Δv1 ^a and the final second offset Δv2 ^a , use the final first offset Δv1 ^a and the final second offset Δv2 ^a to replace the first offset Δv1 and the second After the offset △v2, proceed to step 6.

As a preference of the present invention, the optical density parameter of the notch filter of the Raman spectroscopic detector is 6.5-7.5.

As a preference of the present invention, it also includes placing the method in a darkroom to pre-execute the steps 1 to 6 for pre-calibration before performing the operations of the steps 1 to 6.

As a preference of the present invention, the steps 1 to 6 of the pre-calibration further include using a standard incandescent lamp to provide background light for preliminary calibration in a light environment.

As a preference of the present invention, when the second offset Δv2 has a value of 0, the result is directly output without correction in step six.

As a preference of the present invention, when the first offset Δv1 is 0, the second offset Δv2 is directly used in the step 6 to correct the Raman spectrum of the detection result.

As a preference of the present invention, said standard reference substance is polystyrene.

In summary, the present invention has the following beneficial effects:

The invention has the advantages of many calibration references, high calibration degree and good real-time performance.

Description of drawings

FIG. 1 is a flowchart of the operation of an embodiment of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, the first embodiment of the present invention includes the following steps,

Step 1, use the Raman spectroscopic detector to sample the signal of the standard unified test time T time period on the standard reference substance to obtain the reference spectrum S1, wherein the standard reference substance is polystyrene, and the notch filter of the Raman spectroscopic detector The optical density parameter of the sheet is 6.5-7.5;

Step 2, use the Raman spectrometer to sample the signal of the substance to be detected in the T time period to obtain the initial spectrum S2;

Step 3, use the Raman spectrometer to sample the signal of the empty sample pool for a time period of T to obtain the current background spectrum S3;

Step 4: Calculate the first difference spectrum Sd1 between the reference spectrum S1 and the initial spectrum S2, calculate the second difference spectrum Sd2 between the reference spectrum S1 and the current background spectrum S3, and calculate the third difference between the initial spectrum S2 and the current background spectrum S3 Spectrum Sd3;

Step 5: Determine the reference laser spectrum peak and the laser spectrum peak of the object to be detected according to the second difference spectrum Sd2 and the third difference spectrum Sd3 respectively, and determine respectively according to the center positions of the reference laser spectrum peak and the laser spectrum peak of the object to be detected The first offset △v1 and the second offset △v2 between the laser wavelength and the reference laser wavelength given by the Raman spectrometer during the two sampling processes;

Step 6, compare the first offset △v1 and the second offset △v2, if they are equal, use the first offset △v1 to correct the Raman spectrum of the detection result vi, the correction method is vi=vi+△v1 If not equal, then determine the difference laser spectrum peak according to the first difference spectrum Sd1, and then determine the second laser wavelength between the laser wavelength in the sampling process of the reference object relative to the laser wavelength in the sampling process of the tested object according to the center position of the difference laser spectrum peak Three offsets △v3, use the third offset △v3 to correct the offset △v1 to get the fourth offset △v4, and finally use the fourth offset △v4 to correct the Raman spectrum of the detection result , the correction method is vi=vi+Δv4. In this step, when the second offset Δv2 is 0, the result is directly output without correction in step six. When the first offset Δv1 is 0, the second offset Δv2 is directly used in step 6 to correct the Raman spectrum of the detection result vi.

In the second embodiment of the present invention, on the premise of keeping all the operation steps of the first embodiment, the operation is added in the fifth step. The operation method is to use the first offset Δv1 to the detection result vf of the standard reference object Perform the correction directly, and compare the correction result with the standard Raman spectrum. The standard Raman spectrum is the standard Raman spectrum of polystyrene in theory. After comparison, the fifth offset △v5 is obtained, and the fifth offset △ v5 corrects the first offset △v1 and the second offset △v2 to obtain the final first offset △v1 ^a and the final second offset △v2 ^a , using the final first offset △v1 ^a Step 6 is performed after replacing the first offset Δv1 and the second offset Δv2 with the final second offset Δv2 ^a .

Embodiment 1 and Embodiment 2 of the present invention are placed in the darkroom before performing steps 1 to 6 for pre-calibration. The purpose of pre-calibration is to eliminate the occurrence The pre-calibration must ensure that △v1～△v5 are all 0 values. Steps 1 to 6 of the pre-calibration also include the use of a standard incandescent lamp that has been tested for light parameters by an integrating sphere and meets the requirements of a standard light source to provide background light for preliminary calibration in a light environment. The factory light environment calibration is carried out by shift amount.

This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contribution as required after reading this specification, but as long as they are within the rights of the present invention All claims are protected by patent law.

Claims (8)

1. a kind of Raman spectrum detector calibration method, it is characterised in that：Including following operating procedure,

Step 1 carries out standard reference material using Raman spectrum detector the signal sampling of T time section, obtains reference spectra S1；

Step 2 using Raman spectrum detector to being carried out the signal sampling of the T time section by object to be detected, obtains initial light Compose S2；

Step 3 carries out vacant sample cell using Raman spectrum detector the signal sampling of the T time section, obtains current Background spectrum S3；

Step 4 calculates the first difference spectrum Sd1 of the reference spectra S1 and the initial spectrum S2, calculates the reference light The second difference spectrum Sd2 of S1 and current background spectrum S3 is composed, calculates the initial spectrum S2 and the current background spectrum S3 Third difference spectrum Sd3；

Step 5, respectively according to the second difference spectrum Sd2 and the third difference spectrum Sd3 determine reference laser spectral peak with It is true according to the center difference of the reference laser spectral peak and the object laser spectral peak to be checked respectively by object laser spectral peak to be checked Fixed first offset △ v1 and the second offset △ v2；

Step 6, the first offset △ v1 and the second offset △ v2, if equal using described first partially Shifting amount △ v1 are modified the Raman spectrum of testing result；Difference is determined according to the first difference spectrum Sd1 if unequal It is worth laser spectral peak, third offset △ v3 is then determined according to the center of the difference laser spectral peak, use the third Offset △ v3 are modified to obtain the 4th offset △ v4 to the offset △ v1, finally using the 4th offset △ V4 is modified the Raman spectrum of testing result.

2. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：The step 5 is also wrapped Including will use the first offset △ v1 to be directly modified the testing result vf of the standard reference material, and be tied correcting Fruit obtains the 5th offset △ v5 after being compared with standard Raman spectroscopy, using the 5th offset △ v5 to described first Offset △ v1 and the second offset △ v2 are modified to obtain final first offset △ v1^aWith final second offset △v2^a, use the final first offset △ v1^aWith the final second offset △ v2^aReplace the first offset △ Step 6 operation is carried out after v1 and the second offset △ v2.

3. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：The Raman spectrum The optical density parameter of the notch filtering light piece of detector is 6.5~7.5.

4. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：It is additionally included in and carries out institute It is first placed in dark place before the operation of one~step 6 of the step of stating and first carries out the step 1~preposition school of step 6 progress in advance It is accurate.

5. a kind of Raman spectrum detector calibration method according to claim 4, it is characterised in that：The preposition calibration Step 1~step 6 is further included has carried out luminous environment preliminary calibration using standard incandescent lamp offer bias light.

6. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：When the described second offset When measuring △ v2 as 0 value, result is directly exported without correcting in the step six.

7. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：When the described first offset When measuring △ v1 as 0 value, directly the Raman spectrum of testing result is carried out using the second offset △ v2 in the step 6 It corrects.

8. a kind of Raman spectrum detector calibration method according to claim 1, it is characterised in that：The canonical reference Object is polystyrene.